At the start of the game, construct 3 barracks, supply depots and scvs. Keep the pressure upon the enemy by bunkering his base and attacking a squad of about 12 marines or more at a time. This pressure will buy time to construct 3 more barracks and scvs and supply depots. This time go for gas, upgrade infantry weapons and upgrade U-238 shells. Attack now with about 20 marines, 2 medics and keep bunkering. You should consider expanding now. Keep pumping marines and try attacking this time with 30+ marines and 4 to 6 medics and 6+ firebats. Save gas and go up the tech tree towards physics lab. Grab a second gas spot and minerals with an expansion base. Now keep pressuring but lessen the troops you send and build three starports with control towers. Research yamato gun, by this time you must have an army of 40 plus marines and 8+ medics. Build a fleet of battlecruisers, at about 6+ battlecruisers, dash through the enemy base. Keep marines under the battlecruisers and destroy anti air units.